Quote History Quoted:
My 2011 6920 came out after Colt discontinued the LE only stamping on the receiver. The serial number begins with SP.
I see newer 6920's Sn# beginning with LE. Was the SP used for a limited time???
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With the 6920 models they used the SP prefix serial numbers back in 2011 when they changed the model name marking of the 6920 to "Sporter M4 Carbine" but they also used it for a limited time the following year 2012 with 6920 marked "M4 Carbine".
The SP prefix started from the first AR-15 Sporter SP1 model R6000 in 1964.
The LE prefix on 6920 models are more common and there are only a few SP prefix compared with the LE prefix.
I have a SP6920 marked Sporter M4 Carbine and Colt Mfg. made in early 2011 and the serial number is SP500XXX.
My son's newer made in 2012 LE6920 marked M4 Carbine and Colt Defense have the serial number of LE105XXX.